OPALS™ Ratings

Ogren Plant Allergy Scale (OPALS™) is a science based tool that has been developed by horticulturalist Thomas Ogren which designates a rating from 1 to 10 to each plant based on its allergen level.

The OPALS is based on 130 different criteria, including the amount of pollen a plant produces; its potency, size, density, and shape; the weight of the pollen grains; the amount of time the plant is in bloom; and the plant’s average rankings in skin scratch, patch, and sniff tests. The higher the number, the more allergenic the plant.

Plants ranked from one to four are considered low risk; plants with a ranking of 10 have the biggest impact on allergies; these plants are known to trigger hay fever, asthma, and skin rashes.

Here at Queux Allergy Friendly Plants we are proud to be the first plant centre in the world to be certified by SAFE Gardening to use the OPALS rating system.

You can find out more about the OPALS ratings by visiting this website: http://www.allergyfree-gardening.com/opals.html